#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/cdev.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/bug.h>			/* For BUG_ON.  */
#include <linux/cpu.h>
#include <linux/init.h> /* Needed for the macros */
#include <linux/kernel.h> /* Needed for pr_info() */
#include <linux/module.h> /* Needed by all modules */
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/percpu-defs.h>
#include <linux/wait.h>
#include <linux/gpio/driver.h>
#include <linux/atomic.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/kfifo.h>
#include <linux/mm.h>

#define MY_MAX_MINORS  1
#define   DEVICE_NAME  "device name 500"

DEFINE_KFIFO(myfifo, char, 1024);

struct my_device_data {
	unsigned char *buf;
	struct cdev cdev;
};

DECLARE_WAIT_QUEUE_HEAD(wq);

static struct my_device_data my_dev_data;

static int my_open(struct inode *inode, struct file *file) {
	int ret;
	pr_info("a3 my_open \n");
	ret = kfifo_put(&myfifo, 'e');
	ret = kfifo_put(&myfifo, 'n');
	ret = kfifo_put(&myfifo, 'd');
	ret = kfifo_put(&myfifo, '\n');
	return 0;
}

static ssize_t my_write(struct file *filp, const char __user *user_buffer,
		size_t size, loff_t *offset) {
	int ret;
	unsigned int len = 0;
	pr_info("write");
	ret = kfifo_from_user(&myfifo, user_buffer, size, &len);
	if (ret != 0) {
		pr_err("kfifo_from_user error");
		return 0;
	}
	if (len <= 0)
		return 0;
	*offset += len;
	wake_up(&wq);
	return len;
}

static ssize_t my_read(struct file *filp, char __user *user_buffer,
		size_t count, loff_t *offset) {
	int ret;
	unsigned int len = 0;
	pr_info("read");
	ret = kfifo_to_user(&myfifo, user_buffer, count, &len);
	if (len <= 0)
		return 0;
	*offset += len;
	return len;
}

unsigned int my_poll(struct file *flip, struct poll_table_struct *table) {
	int mask = 0;
	pr_info("my_poll \n");
	poll_wait(flip, &wq, table);
	if (kfifo_is_empty(&myfifo)) {

	} else {
		mask |= POLLIN | POLLRDNORM;
	}
	return mask;
}

int my_close(struct inode *inode, struct file *flip) {
	pr_info("my_close \n");
	pr_info("my_dev_data.buf : %s\n",my_dev_data.buf);
	return 0;
}

int my_mmap(struct file *flip, struct vm_area_struct *vma) {
	if (remap_pfn_range(vma, vma->vm_start,
			virt_to_phys(my_dev_data.buf) >> PAGE_SHIFT,
			vma->vm_end - vma->vm_start, vma->vm_page_prot))
		return -EAGAIN;
	return 0;
}

static const struct file_operations my_fops = { .owner = THIS_MODULE, .open =
		my_open, .read = my_read, .write = my_write, .poll = my_poll, .release =
		my_close, .mmap = my_mmap,

};

static dev_t mydev;

static __init int my_init(void) {
	int err;
	unsigned long  addr;
	pr_info("a3 init_module\n");
	err = alloc_chrdev_region(&mydev, 0, MY_MAX_MINORS, DEVICE_NAME);
	if (err != 0) {
		return err;
	}

	cdev_init(&my_dev_data.cdev, &my_fops);
	cdev_add(&my_dev_data.cdev, MKDEV(MAJOR(mydev), 0), 1);
	addr = __get_free_page(GFP_KERNEL);
my_dev_data.buf =(unsigned char*)addr;
	memset(my_dev_data.buf,0,PAGE_SIZE);
	return 0;
}

static void __exit my_exit(void) {
		pr_info("a3 cleanup_module\n");
/* release devs[i] fields */
cdev_del(&my_dev_data.cdev);
		unregister_chrdev_region(mydev, MY_MAX_MINORS);
}

module_init(my_init);
module_exit(my_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andy");
MODULE_DESCRIPTION("andy one-key driver");
MODULE_ALIAS("one-key");
